The present invention relates to a liquid sprayer apparatus, especially of the type utilized in a pulsed spray dampener system.
Various systems have been proposed in the past for applying a fluid to the rollers of printing presses. These fluids may be used, for example, for dampening or cleaning the rollers, or for preventing printing offset. One type system dampens the rollers by spraying a fluid most from nozzle assemblies positioned adjacent the rollers. Typically, a plurality of nozzle assemblies are aligned in a spray bar.
A nozzle assembly which has heretofore been employed is described later in this text in detail in connection with FIGS. 11-13. Briefly, that sprayer assembly is characterized by a nozzle section and a valve having a plunger positioned at an appreciable distance behind the nozzle section. Pressurized fluid is supplied to the valve and is directed to a sump when the valve is closed and to the nozzle section when the valve is open. The plunger is reciprocated by a solenoid to produce a pulsating spray.
When the front sealing face of the plunger becomes worn, it is necessary to disassemble the solenoid mechanism in order to replace the plunger. This is a time-consuming task which must periodically be performed on all of the nozzle assemblies. Moreover, the need to conduct fluid to a sump when the valve is closed results in wasted fluid which must be disposed of. On the other hand, it has been found that if the feature of conducting pressurized fluid to a sump is eliminated, there will occur, upon opening of the valve, an excessive pressurizing of residual fluid remaining in the passage between the nozzle element and the valve plunger which can result in an excessive amount of fluid being sprayed, as well as a dripping of fluid after the valve has been closed. However, by conducting the pressurized fluid to a sump, no pressure build-ups will occur.
Therefore, it would be desirable to provide a sprayer assembly in which the sealing face can be replaced with minimal time and effort, no excessive pressure build-ups occur, and there is no need to dispose of unused liquid.